The term "noble" is used to describe hops that share a particular set of characteristics. Unfortunately, nobody agrees on which characteristics these are, and therefore there is very little agreement on which hops qualify as "noble."
It is generally agreed that to be noble, a hop must have a relatively low total alpha acid content (usually around 2-6 %), and a mild, pleasant aroma. Other characteristics usually cited include:
- low beta acid
- alpha acid to beta acid ratio close to 1:1
- high humulene levels
- low myrcene levels
- poor storage characteristics
Since the growing area affects the character of the hops, even varieties which are considered "noble" in one area generally are not thought to have noble character when grown elsewhere.
Only two varieties of hop are universally considered to be noble:
And two additional varieties are usually, but not always, included in the definition:
However, depending on the brewer and the definition used, the following hops may also be considered noble: